1. Field of the Invention
The present invention is in the field of removal of excess fat by liposuction.
2. Background Information
Liposuction, the surgical procedure for removal of excess fat from storage sites in the body, has grown in popularity with the surge of obesity in the population. Invention of the ultrasonically assisted liposuction apparatus, for example U.S. Pat. No. 4,886,491 to Parisi and Massengill, has made it possible to remove many kilograms of fat in a single procedure, with comparative safety. As removal of fat cells (adipocytes) is permanent, ultrasonic liposuction procedures may well be preferred to repetitive, and generally ineffective, dieting.
Intumescing, or addition of aqueous solutions of various agents to the tissue, is often done prior to the liposuction procedure. Using an ultrasonically assisted internal liposuction modality, the addition of fluid allows for emulsification and easier removal of the fat and liquid aggregate, which has a lower viscosity than fat alone. By localizing the placement and the quantity of the intumescing fluid, treatment specificity and greater surgical precision are realized. The ultrasonic energy provided by the liposuction cannula breaks down the adipocyte cell wall through a combination of mechanisms, including significant localized frictional heat to "melt" the tissue, as well as mechanical tissue separation. The consequence of these effects is that viscous fat within the adipocyte is liberated, and aspiration is facilitated, as compared to a liposuction procedure in which intumescence is not employed.
Silberg has designed and commercialized an externally applied ultrasonic device, to be used after intumescing and prior to conventional liposuction, to aid in preparation for fat removal. The actual liposuction is performed with a conventional suction-only liposuction cannula. Silberg's apparatus provides ultrasonic energy to the patient via an applicator having a surface contact area of 5 or 10 square centimeters. The power is limited to a level less than that which will cause distress to the skin, which appears to be about 100 to 200 watts, or 20 watts per square centimeter, maximum.
Because of physical limitations, such as the inability to achieve high power densities, as well as the need to maintain intimate physical contact with the skin to allow energy coupling to the underlying tissues, it is necessary to apply the ultrasound energy with Silberg's device for a considerable period of time, sometimes for over three minutes at each proposed removal site.
U. S. Pat. No. 5,507,790 to Weiss discloses the use of externally applied electromagnetic or ultrasonic energy to accelerate local fat tissue lipolysis reaction rates. The Weiss patent, however, does not incorporate intumescence, or liposuction, whether with or without the internal application of ultrasonic energy.